Pressing device with an endless strip



Feb; 6, 1945. THQMAS 2,369,089

'PRESSING DEVICE WITH ENDLESS STRIPS Filed A iil 22, 1942' 2 Sheets-Sheet 1 4 W'\ S (5A1 H TV Feb. 6, 1945- P. v. THOMAS 2,369,089

PRESSING DEVICE WITH ENDLESS STRIPS Filed April 22, 1942 2 Sheets-Sheet 2 PM)! VlhcenfTnomo S V TOE.

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the-Jilin; and; onwhiom in most cases, the recorde printing'or operation is eflected.

Q Maxim'umadherence; Rigorouslyuniform unwinding of 'the'iilm; oi introduction of disturbances or'vi- The film must rotation ofsaid'unit entioned'conditions, thatis'to say:

.the rotation.

dricalrollers pressingonthefilm, To'p'roduce the proper adherence, a somewhat high pressure is necessaryrowing to-the small suntace ofcontact I ,between said; rollers and the film, which surface 40' isreduced to the generatrlces of contact of the cylinders. very high pressure acting accorda line whereas adjacent points are not pressed,- isjnot without causing prejudice to the "i imiform unwinding of the film and to the rotation of the cylinder;

One 01' the objects of the present invention consists in eliminating this very high pressure, localized atone point, and to replace it by a medium pressure uniformly distributed by means of an endless stripacting on a large portion AB 0! the surface of the cylinder, portion comprised in the angle a, of Fig. 2 oi the accompanying drawings. The of said angle a is notlimited and can easily reach ahali-circumterenc'e in'certaln 56 ;m;.rotationoi'the'. f

-Flg;"5 isy v I pressingdevicewith,-an endless stripac v. cording'jto the'inventionycompriselsfin Y, 9 ple' "underconsideratlqn; a support '2 constituted i 1 as mmtin e'iorktween hebmn esof him devices generally have one or more cylin- (UNI-"ran; srA'r-sspm wt-mama i jsystem iliereinafter -de' flb d and torming'nthe *subiect-matterot the present invention I lSand-Z' .illustrate in trout elevation, the deviceiormingthe-subiect matter oi the 'inven- 1 "tion in. nonioperating position and in operating position 7 a Figs 3 plan view of the same device.

are;'mountedffrbllers,3"- carrying the endless strip 4. Thenumbe'r (if-rollers 3 whichis two-at I ean' be' increasedlaccordin'g to circumstaiicesiid order toi'ncrease for instance the length or. the arc f contact'AB (see Fig.2).

' The support 2 has a part forming a shoe sliding in two slide-ways Ill nany suitable supporting medium, "so that the'two following conditions are always satisfied: the axis of symmetry of the pressing device, which is also its axis of translation, always passes through the axi of rotation ed! the cylinder I; the axes of rotation of the rollers 3 always remain parallel in all the positions of operation, to the axis of rotation of the cylinder I.

In none of the positions of operation, at no moment whatever, whatever may be the opening of the angle a, must the rollers 3 come in contact with the cylinder I. In the particular case of two rollers, the distance between the axe of the rollers must therefore be greater than D+d, D being the diameter of the cylinder I, all thicksta s l m Pressure he, ndl s flmu m v isteac' d icgl df lare corresponding'sideviews and i nesses of films being included, and at being the maximum diameter of the cheeks of the rollers 3.

The length of the arc of contact AB of the strip 4 with the film or films II and consequently the value of the corresponding angle at the centre are adjusted by the position of support 2 relative to cylinder I. For that purpose, two abutment screws 8 on the support 2 coming in contact with abutments 9 on the supporting medium are provided and allow said adjustment. The pressure of the endless strip on the film and the cylinder l is obtained by means of springs 6 having their lower ends attached at I to the supporting medium, and their upper ends attached to the support 2 and exerting a pull on the member 2, which has the efiect of stretching the endless strip on the cylinder I until the abutment screws 8 touch the abutments 9. At this moment, the length of the arc of contact AB reaches the required value.

The rollers 3 are mounted, as above explained, in such a manner that in all the positions of operation, their axes remain rigorously parallel to the axis of th cylinder I which they must never touch. They must run rigorously true and have the least possible resistance to rotation. As shown in the drawings, the rollers 3 are mounted on anti-friction bearings 5. The needle screws of these bearings are only diagrammatically illustrated and can have any other shape in particular at the end-supporting the roller (cylindrical bearing, etc.) Any other bearing system can be contemplated, as long as it ensures the uniform rotation of the roller and without vibration.

Each roller 3 can have the shape of a grooved pulley or of a roller having cheek members secured in position. It must, without prejudice to gotten that by increasing the diameter, the inertia of the roller is increased.

The endless strip 4 is one of the main parts of the invention. The texture and homogeneity of said strip must remain rigouously constant at all points which successively pass on the are of contact AB. The material constituting said strip must be flexible and resilient so as to be rigorously applied at all points of the cylindrical surface of contact.

Rubber is quite suitable for this purpose, but any other material possessing the required properties of homogeneity, flexibility, resiliency can be employed.

The cross section of the strip can be rectangular, semi-circular, trapezoidal or triangular according to circumstances. Its width must be such that it presses on the greatest possible width of The length of the endless strip depends on the diameter of the rollers and on the distance separating their axes- Whilst complying with the condition above mentioned, according to which the distance between the axes of the rollers must be greater than D+d (in the particular case of two rollers), it is advantageous not to increase too much said distance between the axes. In

fact, if this was so, a vibratory wave might be created of prejudicial amplitude in the parts of the strip between the rollers and the cylinder. Said vibratory wave will be so much the less important as the strip is thicker and as said portions stretched between the rollers and cylinder are shorter.

In position of rest, the endless strip between the two rollers must have a certain amount of slack (Fig. 1). This slack of the strip when at rest will be so much the smaller as the arc surrounded by the strip upon operation, is smaller. The application of the mean which have just been described, allows, as will be understood, of obtaining on a film in -movement, stretched around a rotating cylinder, a uniform pressure distributed over a large surface; it allows of thus increasing the adherence of said film on the cylinder or the adherence of a plurality of films, of

eliminating any slipping and of avoiding, in the rotation of the cylinder and in the unwindin of the film or films, all the vibrations or other disturbances due to the pressing devices usually employed.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a pressing device, mounted on a suitable supporting medium, for applying one Or more films on a rotating and peed regulating cylindrical member mounted on said supporting medium, the combination of a pair of rollers slidably mounted on said supporting medium; an

endless band rove about said rollers; means to urge said rollers toward the cylindrical member to press the band against the film on the surface of the cylindrical member; and adjustable means to limit the movement of the rollers, the measure of the arc-of contact of the band on the film being determined by the adjustment of said limiting means.

2. In a pressing device, mounted on a suitable supporting medium, for applying one or more films on a rotating and speed regulating cylindrical member mounted on said supporting medium, the combination of a slideway on said medium; a carrying member slidable in said slideway and comprising a pair of forks; a roller journaled in each fork, the parts being so disposed that the axes of the rollers are constantly parallel to the axis of the cylindrical member; an endless band rove about said rollers; a pair of springs, each having one end attached to one of said forks and its other end attached to the supporting medium, said springs being adapted to urge the carrying member toward the cylindrical member; a pair of abutments on the supporting medium; and an adjustable stop member on each of said forks and adapted to co-operate with one of said a'butment to limit the movement of the carrying member toward the cylindrical member, the parts being so related that the endless band is pressed, by action of the springs, against the film on the surface of the cylindrical member, the measure of the arc of contact of the band on the film being determined by the adjustment of the stop members.

- PAUL VINCENT THOMAS. 

